Multiple output sequential signal source



Sept. 4,

Filed Apr CHANNEL OUTPUT PULSES J. F. BRINSTER ETAL MULTIPLE OUTPUTSEQUENTIAL SIGNAL SOURCE 25 VOLTAGE WAVE SOURCE Fig. l

CHANNEL NO.I

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T PULSES 3| CHANNEL No.2

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SAMPLING PULSE SEQUENCE IIIIJIIIII I- FRAME 'I Fig.3B

Inventors f w W Agent Sept. 4, 1962 .1. F. BRINSTER ETAL 3,052,871

MULTIPLE OUTPUT SEQUENTIAL SIGNAL SOURCE Filed April 2a, 1958 5Sheets-Sheet 2 CLOCK PU LS ES Fig. 5

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John F. Brinsfer Inventors Walter C. Johnson P 1952 J. F. BRINSTER ETAL3,052,871

MULTIPLE OUTPUT SEQUENTIAL SIGNAL SOURCE Filed April 28, 1958 5Sheets-Sheet 3 SAMPLING COUNTER OUTPUTS SAMPLING E T NS To BUSSES SECOMBINED PULSE F X X XXXX XXXX

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64 TIME EFFECTIVE i BUS POTENTIALS, 3 (4) SAMPLING PULSE -o.|

FRAME Fig. 1|

John F. Brinster Walter C. Johnson By KM Agent Inventors Sept. 4, 1962J. F. BRINSTER ETAL. 3,052,871

MULTIPLE OUTPUT SEQUENTIAL SIGNAL SOURCE Filed April 28, 1958" 5Sheets-Sheet 4 63 z Q 7 I I7 I H CLOCK I i I l 2 2 3 3 PuLSES W I T T TT T T 85;IF 1x T T Q BUS I,2- BUS I,2- BUSl,2" susflzj S9 EOSEM Bus 34'BUS3(4') 93 95 BUS I123; 92 Fi 9 SAMPLING PuLSES CHANNEL NO.I

SAMPLING I 2 3 PERIOO NOS. [*T T] IOHH y I MODIFIED CLOCK PULSES I I I I1 I EFFECTIVE O l I TIME BUS POTENTIALS, SAMPLING PULSE NO.I FRAME Fig.I3 SAMPLING PERIOD NOJ P425 EFFECTIVE A BUS POTENTIALS, SAMPLING PULSENO.I E FRAME Fig. ITA

SAMPLING PERIOD NOJHIZ? J- EFFEcTIvE I BUS POTENTIALS, A F 2 I 3 (4)SAMPLING PuLsE NO.I FRAME Fig. I'IB By 1A Agent Inventors Sept. 4, 1962F. BRINSTER ETAL 3,052,871

MULTIPLE OUTPUT SEQUENTIAL SIGNAL SOURCE Filed April 2a, 1958 5Sheets-Sheet 5 ;9? 32 m PULSE 40' 7 1 f Igg DURATl0N L Ill 2:2 3:3 4:4

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I5 R CHANNEL 6 1 BUS 3' 4' 1 w? CLOCK 1 a PULSES |'22'3i344' CHANNEL 2 Ii l I 2 COUNTER w Bus OUTPUT A I BUS 0 797 COUNTER i- PULSE I07'-DURATION OUTPUT A 5; 2 CONTROL 105 L C Fig. l6

PULSES PULSE DURATION (DUTY CYCLE) CONTROL COUNTER 32 I21 7 I m i iCLOCK .L

, N3 N5 PULSE I 16 I 1 W I I i i i AiA' l liJ' 2E2 33' 44' I i 1 i 1 l JBUS A if A if BUS A Bus 314'] TIT ITIIBUS 2I 1r 1: BUS A,|',2',3' 1 H23SAMPLING PULSES CHANNEL No.

John F. Brinster Inventors Walter C. Johnson y 14 M Agent United StatesPatent Ofi ice 3,%52,87l Patented Sept. 4, 1962 3,052,871 MULTIPLEOUTPUT SEQUENTEAL SIGNAL SQURCE John F. Brinster and Walter C. Johnson,Erinceton, N1, assignors to General Devices, the, Princeton, NJ acorporation of New Jersey Filed Apr. 28, 1958, Ser. No. 731,507 7Claims. (Cl. 340-167) This invention relates to electrical circuit meansfor producing a plurality of electrical impulses in selected timesequence, for example impulses which may serve as the agency forefiecting the repeated sampling of the electrical signals of a pluralityof information channels.

An earlier filed application for patent in the names of the presentinventors entitled Multi-Signal Sampling Circuit, Serial No. 712,576filed, January 31, 1958, now US. Patent No. 2,958,857, discloses aswitching or sampling circuit in the operation of which the times ofoccurrence and the duration of the periods over which sampling isperformed are controlled by recurrent sequences of short pulses, eachpulse being formed by combining selected portions of two or moretime-displaced periodic voltage waves of like period. Circuit means forforming such pulses, particularly from a polyphase A.C. supply, arefurther disclosed in another application for patent in the names of thesame inventors filed concurrently with said first application entitledPulse Sequence Generator, Serial No. 712,575, now U.S. Patent No.2,861,202.

in the circuits of the two cited applications certain circuit elementswhich have the function of selecting the portions of the voltage wavesthat are combined to form the sampling pulses appear in circuit once foreach use of a wave in forming such a pulse. Thus, if two dioderectifiers, for example, are required to form a pulse from a combinationof portions of two voltage waves, three rectifiers are required incombining three waves and the total number of rectifiers required is thesum of those required to form each pulse of the sequence. The presentinvention in one of its aspects, represents an improvement over suchearlier disclosed circuits in that the number of circuit elements oflike character required to effect the formation of the sampling pulsesdoes not increase in proportion to the total number of times the severalvoltage waves are used in combination but at a lesser rate, therebyeffecting a saving in the cost of these elements themselves and a savingin their interconnection, together with a reduction in the spaceoccupied by the assembled apparatus. This last feature is highlydesirable in many applications of sampling apparatus such as missile andair-borne vehicle telemetry, where space efiiciency is a primeconsideration.

The present invention has additional advantages which include thepossibility of ready adjustment of the duty cycle of the recurrentsampling pulses.

Accordingly, it is an object of the invention to provide a multipleoutput sequential signal source of improved design and of decreasedcost.

It is another object to provide signal sampling apparatus whereinsampling pulses are derived from a plurality of periodic voltage waveswith improved efliciency in the use of circuit elements.

it is another object to provide apparatus of the above characterwherein, for reasons of efliciency in the use of circuit elements,provision is made for utilizing precombinations of certain of thesupplied periodic voltage Waves before effecting the ultimate formationof the sampling pulses.

It is another object of the invention to provide apparatus of the abovecharacter in the operation of which the generated sampling pulses areperiodic in character and their duty cycle is readily adjustable.

A further object is to provide apparatus of the above character whichmay also serve to distribute to a plurality of output circuits sequencesof pulses occurring at a common input.

These and other objects and advantages of the invention will be moreclearly appreciated upon consideration of the following description ofcertain preferred forms which the invention may take, furtherillustrated by the accompanying drawings in which:

FIG. 1 is a diagram illustrating a type of circuit in which theinvention finds utility;

FIGS. 2A and 2B are wave diagrams illustrative of the operation of thecircuit of FIG. 1;

F168. 3A and 3B are diagrams showing the type of sampling pulses thatare utilized in the circuit of FIG. 1 and certain disclosedmodifications thereof;

FIG. 4 is a modification of a portion of the circuit of FIG. 1illustrating the pie-combination of supply voltage waves;

PEG. 5 is a block diagram of a binary counter comprising a feed-backconnection and a plurality of output connections;

FIG. 6 is a series of wave diagrams relating to the operation of thecounter of FIG. 5;

FIG. 7 is a table showing the connections requiring to form samplingpulses for a twelve channel system, according to the circuitarrangements of FIG. 1;

FIGS. 8A and 8B are diagrams respectively illustrating the formation oftwo successive sampling pulses of a frame through the operation of thecircuit of FIG. 1;

FIG. 9 is a diagram of a modification of the circuit of FIG. 1, inaccordance with the principles of the invention, providing forpro-combination of certain of the supply voltage waves;

FIG. 10 is a table of connections relating to the circuit of FIG. 9;

FIG. 11 is a diagram illustrative of the formation of pulses by means ofthe circuit of FIG. 9;

FIG. 12 is a modification of the circuit of FIG. 9, providing forsampling pulse duty cycle control;

FIG. 13 is a series of Wave diagrams illustrative of the operation ofthe circuit of FIG. 12;

FIG. 14 is a modification of the circuit of FIG. 12, showing additionalcircuit elements;

FIG. 15 shows another modification of the circuit of PEG. 12; and

FIGS. 16, 17A and 17B are wave diagrams illustrative of the operation ofthe circuit of FIG. 15.

By way of illustration of one type of switching or sampling circuit withwhich the present invention is concerned there is shown in FIG. 1(generally similar in arrangement to FIG. 7 of said application SerialNo. 712,576) a source 11 of the signal of a No. 1 information channeland a source 13 of a No. 2 channel signal. In certain applicationsprovision may be made for sampling to or more such signals in repeatedsequence, one complete sequence of signal samples, and also the periodthereof, being referred to herein as a frame, in conformity withtelevision and like terminology.

Source 11 is connected to a junction point R by a lead including aresistor 15. The variable potential of point R is the prototype of thesampled No. 1 channel signal transmitted to output circuit 17 by way ofrectifier 19, as will be further explained. Point R is, in addition,connected to terminals of like character of two diode rectifiers 21 and23, polarized as shown. The opposite terminals of rectifiers 21 and 23are connected to sources 25 and 27, respectively, which supply the twovoltage waves that in the illustrated case are combined to form thechannel No. 1 sampling pulses. Similar circuit means are provided toform the other sampling pulses and to supply in sequence to circuit 17,over lead 18, the sampled signals of the other channels resulting fromtheir operation. The sequence, within a frame, in which the samplesignals of the various channels appear in circuit 17, as on lead 20thereof, is determined by the time sequence in which the severalsampling pulses are formed.

The operation of the circuit of FIG. 1 in sampling signals of assumedform of the two channel waves there shown is illustrated, forpositive-going signals, by the wave diagrams of FIGS. 2A and 2B.Assuming the impedance of voltage wave sources 25 and 27 to be lowcompared to the combined impedance of source 11 and resistor 15, thenwhen either of these sources 25 or 27 is at or below ground potentialthe associated diode rectifier, 21.or 23 as the case may be, is in aconducting condition and point R also is at or below ground potential.At such time substantially zero voltage appears in output circuit 17.When, however, the voltage waves of sources 25 and 27 simultaneouslyhave values more positive than that of the signal, diodes 21 and 23 bothare rendered substantially non-conducting and the potential of R risesto a value proportional to the signal value. The portion of the variablepotential of point R appearing at circuit 17 constitutes the sample No.1 channel signals or pulses 29, seen in FIG. 2A. The similarlylgenerated No. 2 channel sample signals or pulses, 31, displaced to alater time relative to No. 1 channel signals 29, are seen in FIG. 2B. Itis to be noted that the controlling portions of the voltage wavesfurnished by sources 25 and 27 are those which successively, at eachinstant, have the more negative value and it may be considered that itis a combination of these more negative portions, which in effectconstitutes the periodically repeated sampling pulses. This formation ofsampling pulses is later described herein with reference to FIGS. 8A and8B and other figures. The sequence of sampling pulses in a frame,without pulse separation (100 percent duty cycle), is shown, by way ofexample, in FIG. 3A and with pulse separation (less than 100 percentduty cycle) in FIG. 3B. In the figures herein no absolute 'value isassigned to the upper or lower levels of the several waves illustratedsince this is adjustable by the use of a bias. Thus, as is sometimesdesirable, the sample signal output may have a negative pedestal or alower level below ground potential when the sampled signal has zerovalue.

The voltage waves supplied by sources 25 and 27 and their counterpartsin the cases of the other channels may, in general, have any periodicform. In previously cited application, Serial No. 712,576 thecombination of waves which comprise pulses of rectangular shape isreferred to and is illustrated in FIG. 4 of said application. Sourcesfurnishing waves of this form are assumed in describing the operation ofthe circuits disclosed herein. These waves are termed, for convenience,square waves and their component pulses are characterized as of squareform, regardless of their duty cycle or'the relationship of amplitude toduration.

In the embodiment in the invention now to be described which, as above,will be referred to as a signal sampling circuit, although obviously notlimited to such use, the waves that are combined to form the samplingpulses are considered for purposes of description to originate at aseries of busses or junction points the potentials of which, in certaincases, may be the result of an earlier combination. of two or moresquare waves. The primary voltage waves of which such precombinationsand ultimate combinations are made may directly or indirectly be derivedfrom a binary counter or counters actuated by recurrent clock pulses,advantage being taken in such case of the square waves of difierentduration and timing which characterize the potentials at dilferentpoints along a binary counter chain. Transistorized bistable elementsare the preferred form of counting units in the chain, on the basis ofspace eificiency and for other reasons.

As an example of an arrangement adapted to generate pulses for samplingthe signals of a twelve channel system, there is shown in FIG. 5 acounter 32 comprising a chain of four binary counting units, 33, 35, 37,and 39, each adapted to supply in known manner, by means of suitableconnections, two square wave outputs of opposite phase when the chain isdriven by recurrent input clock pulses on lead :0. These are the primarywaves to be combined in building the sampling pulses. In the blockdiagram representation of the figure the two halves of a counting unitrespectively capable of supplying these two outputs are distinguished bythe use of unprimed and primed numerals, as, 1, 1', 2, 2, etc. The samenumerals are used herein in referring to the respective outputsthemselves. Further, for conciseness, these numerals are at time appliedto the stable states of the binary units which result in outputstherefrom of selected sign. The sign convention followed in such casesis that where a binary stable state is identified by a particularnumeral, it is that state in which the output of the binary half alsoidentified by that numeral is more positive than the output of the otherhalf. Thus, state 1' implies that at a given instant output 1' of binary33 on lead 54 is more positive than output 1 on lead 53. According tothis notation the state of the entire counter at some particular timemight be designated as: 1, 2, 3,, 4', meaning that the outputs of thebinary halves respectively designated by these numerals aresimultaneously positive, relative to the associated outputs of thecoacting binary halves.

Binary unit 33 is actuated by positive-going clock pulses appearing onlead 40, each of which produces a change of state of the unit, andsupplies a positive-going switching pulse from the half thereofdesignated 1 to binary 35 upon the occurrence of alternate clock pulses,the other binary units (in the absence of modifying means) counting downwith a scale of 2 in similar conventional manner. Since the chain ofFIG. 5 comprises four binary units, the scale for the entire chain wouldbe 16 were it not for a feedback connection 61 from binary half 4 tobinary half 3, by way of diode rectifier 63 polarized as shown. Suitablyapplied in known manner, as later re ferred to, this connection, whichillustrates means for binary counting with a scale other than a power of2, reduces the combined scale of binary 37 and binary 39 from 4 to 3,the over-all counter scale then being 2 2 3=12. Scale changing meansother than the illustrated feedback connection are known.

In general, a counter of n binary counting units can supply a maximum of2 distinctive combinations of the outputs of the binary halves thereof.In countin g with a scale which is not a power of 2, a feedbackconnection or its equivalent renders certain of these combinationsimpossible of existence. In the circuit of FIG. 5, assuming that theactive elements of the counting units are p-n-p transistors with thefeedback connection 61 made between the collectors of the transistors inbinary halves 4 and 3 by way of rectifier 63, then, among other results,this insures that the output of binary half 3 is always positive whenthat of 4 is positive, and thus makes it impossible for the output of 3,the other half of binary 37, to be positive at such time. In the adoptednotation which identifies the state of a binary unit with the numberassigned to the output therefrom, when positive, this can be expressedby saying that no state of counter 32 as a whole is possible in whichthe combination 3', 4 appears. The counter merely skips these states.

The waveforms of the several outputs supplied by counter 32 (assumed tobe of like amplitude), are shown in FIG. 6, together with the clockpulses that actuate the counter. In this figure the chosen origin oftime (at the left of the wave diagrams) is the instant when the counteris about to assume the state 1', 2', 3', 4. The waveforms of outputs 1,1 and 2, 2' of binary units 33 and 35, respectively, appear in thefigure as in the case of normal binary counting but the duration andrelative timing of outputs 3, 3 and 4, 4' of binary units 37 and 39,respectively, are afiected by the feedback connection 61.

The table of FIG. 7 shows the groupings of the outputs derived fromcounter 32which enter into the formation of the twelve sampling pulsesper frame required in the presently considered example and the wavediagrams of FIGS. 8A and 8B respectively illustrate the formation of thefirst and second pulses of a frame. For example, it is seen in FIG. 8A,considered in connection with FIG. 6, that output 1 of the half ofbinary 33 similarly designated, forms the positive-going pulse 64, whichoccupies a complete sampling period, and that subsequently, asindicated, outputs 2 and 3' are efiective to hold the sampling wavelevel at Zero (or other selected reference potential) for the remainderof the frame. This is in accordance with the explanation of theoperation of the circuit of FIG. 1, and particularly of thewave-combining rectifiers therein, where it was noted that it is therelatively most negative portions of the combined primary voltage waves,as these Waves vary with time, that, pieced together, form the contoursof the sampling pulses. In FIG. 8B the second sampling pulse 66 of aframe is seen to be formed by counter output 1 while outputs 2 and 3'maintain zero level during the remaining period of the frame. For theduration of each sampling pulse applied to a channel the circuit isconditioned to transmit the signal of that channel to the outputcircuit.

In the following through the formation of the various sampling pulses,again with reference to the wave diagrams of FIG. 6, it will be foundthat the portion of a frame during which output 4 is negative includesthe portion during which output 3 is negative, and that, relatively,output 4 is always at least as negative as 3. Hence, in pulse formation,the blanking or zeroing effect of the negative or low level portions ofoutput 3 can as well be obtained by the use of output 4. Similarly,output 3' is always at least as negative as 4'. This is expressed hereinby enclosing in parenthesis the numeral designating the includedsuperfluous output, as (3)4 and 3'(4'). Advantage may be taken of thisrelationship to simplify the wiring of the sampling pulse circuit.

If sampling pulse formation for a twelve channel system were carried outby means of a circuit of the type of FIG. 1 the connections to thevarious counter outputs would be as shown in the table of FIG. 7,different numbers of waves being here combined in forming differentsampling pulses in a frame. Since each connection to a counter outputrequires a rectifier, as rectifier 21 of FIG. 1, the total number ofcombining rectifiers in this case would be 40. This is the number calledfor in the straightforward method of connection of the prior art. It maybe seen, however, that certain groupings of outputs are used more thanonce, as the combinations 1', 2'; 1, 2', etc. In FIG. 4 there is shownan example of a circuit arrangement for effecting pre-combinations ofcounter output wave groups such that the successively most negativeportions of the combined waves appear as the potentials of a series ofbusses or junction points which may be considered to constitute newsources, comparable to the original binary halves, which are availablefor supplying square waves for further combination. Thus, the voltageWaves supplied by sources 65 and 67 are combined, through the operationof rectifiers 69 and 71, respectively, to supply the variable potentialof bus 73, which like the combined Waves, is a square wave. Similarly,the waves supplied by sources 75 and 77 are combined as the potential ofbus '79. In the ultimate formation of the sampling pulses, the squarewaves of busses 73 and 79 may then be combined, as to their relativelymore negative portions, by Way of rectifiers 81 and 83, respectively.

It is found that the use of such pre-combinations of two or more voltagewaves results in a saving in the total number of rectifiers required(usually crystal diodes) which saving, generally, is greater the greaterthe number of channels sampled per frame. In FiG. 4 the pre-combinationof only two voltage waves is shown but, in systems comprising a largenumber of channels pre-combinations of a greater number of waves tosupply the 6 various pre-combination hus potentials may proveadvantageous, from the standpoint of circuit element economy.

F G. 9 shows a circuit arrangement adapted for effectingpre-combinations of waves in a twelve channel sampling system inaccordance with the principles of the invention and according to onescheme of wave combination, the same outputs of counter 32 (FIG. 5)being employed as are combined by the connections listed in the table ofFIG. 7. Other schemes may be adopted. The connections for ultimatelyforming the sampling pulses for channel No. 1, only, are shown in FIG.9, to simplify the diagram. Thus, outputs i and 2 are combined, as totheir more negative portions, by way of rectifiers and 87 to supply thepotential of bus 89. The square waves of lbusses 8? and 91, the lattersupplied by output 3/(4'), then are combined by way of rectifiers 93 and953, respectively at bus 92 to form the No. 1 channel sampling pulses.Other sampling pulses comprising the wave combination 1, 2 are formed bya connection to bus 39 instead of by separate connections to the primarywave sources energizing that bus. FIG. 11, analogous to FIG. 8A, showsthe bus potentials effective over the period of a rame in forming achannel No. l sampling pulse 64-" in this manner.

The table of FIG. 10 shows the connections to the several busses of FIG.9, either rare-combination busses or busses supplied by a single counteroutput, that are required to form the twelve sampling pulses per frameof the present example, using the type of ircuit generally illustratedby FIG. 4. The saving in rectifiers made in this example may lbEreckoned as follows: Without effecting pre-combinations of waves, atotal of 40 connections, each including a diode rectifier, is required(FIG. 7). This is in accordance with the prior art. In the arrangementof FIG. 9, in accordance with the improvements of the present invention,there are required 10 diodes to supply the potentials of therare-combination busses and, as seen in the table of FIG. 10, there arerequired 24 connections, each including a diode, to combine thesepotentials and those of the single wave busses (3)4 and 3'(4), making atotal of 34 diodes. While only 6 diodes are saved in the relativelysimple circuit here selected by way of example, the saving increasesrapidly and may become very large with increase in the number of sampledchannels, particularly where it is possible to employ pre-combinationsof more than two waves.

Duty Cycle Control The principle of the pro-combination of voltage wavesand the availability of pro-combination busses in apparatus making useof this principle make it a relatively simple matter to adjust orcontrol the duty cycle of the sampling pulses that is, the proportion ofthe assigned full sampling period per channel occupied by these pulsesOn the top line of FIG. 6 there is shown a sequence of 106 percent dutycycle samplin pulses such as might result, for example, from employmentof the connections of FIG. 9. The signal samples obtained from theiroperation likewise will have a 190 percent duty cycle so that thesignals of successively sampled channels, as they appear in the outputcircuit, are unspaced, one from another. The circuit modifications ofFIGS. l2, l4 and 15 show arrangements for obtaining duty cycles of lessthan percent.

In FIG. 12 again only the connections for forming the pulses forsampling the No. 1 channel signal are shown, to simplify the diagram.The connections for forming the other pulses of a frarne are similar. Asseen in this figure Modified Clock Pulses are supplied by Pulse DurationControl 97 to lead 4%, corresponding to lead 49 of FIG. 5, and aconnection is made from this lead to a bus or junction point 99,designated bus 9 in the figure, which is comparable to the busses ofFIG. 9, two of which, busses 1', 2' and 3(4'), also ap- 7 pear in FIG.12. The sampling pulse for channel No. l is then formed by means ofconnections to busses 1', 2'; and 3 (4'), respectively, and appears atbus 139, designated bus 0, 1', 2, 3'.

Referring to FIG. 13, the top line shows the wave of Modified Clockpulses which includes pulse 191. These pulses have a width or durationless than that of a full sampling period for one channel while for theremainder of the period the pulse wave is at its herein unassigned lowerlevel. Pulse Duration Control 97 (FIG. 12) which supplies the ModifiedClock Pulses as an output, may have a variety of forms, one known formbeing a monostable multivibrator which permits a continuuous adjustmentof output pulse width. A different means for discontinuous adjustment ofpulse width, is described later herein.

Whenever the voltage or potential wave at bus 99 of FIG. 12 (bus 9) hasthe most negative value of the waves 0, 1', 2', 3 combined at bus 100,it becomes the controlling factor in the formation of the No. -1 channelsampling pulses. The bottom line of FIG. 13 illustrates the'elfect ofthis wave in decreasing the duration of the sampling pulse for channelNo. 1 to a value less than a full assigned channel sampling period. Asimilar effect is achieved through the use of the bus t wave in formingthe other pulses of a frame, as indicated by the dashedline pulses ofthe diagram. The different portions of a frame over which the severalcombined voltage waves are effective in forming the complete wave of thefirst sampling pulse are identified in FIG. 13 in the same way as inFIG. 11.

A second circuit modification providing for sampling pulse duty cyclecontrol, and one that requires fewer circuit elements than that of FIG.12, is seen in FIG. 14. This figure is similar to the complete samplingcircuit of FIG. 1 in that it indicates the sources of the channelsignals and the path for supplying the sample signals to the commonoutput or load circuit 17 which includes lead 18. Here, the voltage waveof bus 105, designated bus 0 in correspondence with FIG. 12, is derivedfrom a repetitive clock pulse input on lead 107 by way of Pulse DurationControl 97', which may have any of the features referred to inconnection with similar means 97 of FIG. 12 and which likewise producesoutput pulses of seletively less duration than a complete channelsampling period. The voltage wave of bus 105 is applied to lead 18 ofthe common output circuit by way of rectifier 109, polarized as shown.There it is combined with and modifies the form of each of the samplechannel signals as they appear in sequence on lead 18, instead of beingcombined with the individual sample signals before they reach a commonpath as described in connection with FIG. 12. Otherwise the operation ofthe two circuits is closely alike and the ultimate results produced arethe same.

FIG. 15 presents a further circuit modification affording sampling pulseduty cycle control. Here there is shown instead of or as a modificationof Pulse Duration Control 97 of FIG. 12, a binary counter circuit 111which precedes counter 32 of FIG. 12, for instance. Circuit 111 includestwo binary counting stages 113 and 115, respectively, together with afeedback connection 117, comprising rectifier 119, which reduces thecombined counting scale of the two units to 3, in the manner previouslyreferred to in connection with counter 32. Circuit 111 is driven byclock pulses on input lead 121 and binary unit 115 thereof suppliesoutput pulses for driving counter 32 and also supplies two outputs fromthe halves thereof respectively designated A and A, these last outputs,as before, each being referred to by the letter of the binary halfproducing it.

The wave forms of a partial sequence of clock pulses of assumed durationon lead 121 and of resultant counter out-puts A and A, are shown in FIG.16, on the top and bottom lines, respectively. The formation of thecounter outputs occurs in the manner described in connection with thoseof counter 32. It will be found by following through a similar analysishere that the pulses of outputs A and A have a duration which is onethird of that of the outputs of binary halves 1 and 1' of counter 32,the latter duration being the complete sampling period per channel. Whenthe connections of FIG. 15 are used to combine counter outputs A, 1, 2'and 3 at bus 123 the samplying pulse formed (the first pulse of a frame)may be as shown in FIG. 17A. This pulse 125 occupies onethird of thecomplete sampling period, or has a 33 and /3 percent duty cycle. If theoutput of binary half A is used for combining purposes instead of thatof half A, by connection to bus A, then the sampling pulse formed, pulse127 of FIG. 17B, will'occupy two-thirds of the complete sampling period,a duty cycle of 66 and percent. Thus, by utilizing various countercircuit arrangements ahead of the previously described counter 32 ofFIG. 12 and other figures, sampling pulse duty cycles can be obtainedwhich divide the complete sampling period per channel into complementaryfractional parts as: /2 and /2; /s and A; A and %1; etc. In terms ofpractical circuit assemblies this means that a basic sampling circuitcan be made up to give percent duty cycle sampling pulses, using theequivalent of counter 32, and then the output of this circuit can bemodified, as to duty cycle, merely by adding the requisite pro-countercircuit, with suitable connections thereto.

The descriptions herein of certain forms which the invention may take,and of their operation, have made reference to the sampling ofpositive-going information signals and the supplying of positive-goingoutput sample pulses. It will be recognized that this is compatible withthe illustrated polarizations of the various rectifiers employed butthat other rectifier polarizations will render the described circuitssuitable for the sampling and supply of other types of pulses.

Also, where complete sampling or switching circuits have been shownherein they have been described as serving to collect samples of thesignals of a plurality of sources and to assemble them as a sequence ofpulses in a common output circuit. The same circuit means, however, mayoperate in converse manner to receive a sequence of pulses as an inputand distribute these pulses to a plurality of output circuits, which isanalogous to the dual use to which a mechanical commutator may be put.Thus, referring to the circuit of FIG. '1 by way of illustration, asequence of pulses appearing on lead 20 of circuit 17, now serving as aninput circuit, may be distributed to outputs occupying the circuitpositions of means 11 and 13 through the agency of what have heretoforebeen called sampling pulses produced by a combination of suitablevoltage Waves, as by a combination of the waves supplied by sources 25and 27. I

The embodiments of the invention described herein are illustrative,only, of a wide variety of forms which the invention may take and arenot by way of limitation of the scope of the invention, as set forth inthe appended claims.

What is claimed is:

1. In a circuit for sending out over a single output path recurrentsequences of samples of the variable signals of a plurality ofinformation channels by applying to the channels in sequence samplingpulses conditioning the circuit to transmit said signals to the outputpath for the duration of the pulses, the means for forming said pulseswhich comprises a plurality of sources of primary periodic voltagewaves, means for effecting the combination of a first selected group ofsaid primary waves including leads respectively connected to the sourcesof said waves each having a rectifier therein, said rectifiers beingsimilarly polarized relative to said sources and said leads beingconnected to a common junction remote from said sources relative to saidrectifiers, means for effecting the combination of a second selectedgroup ofgsaid primary waves which includes the resultant of said firstcombination as it appears at said common junction comprising a firstlead connected to said junction to receive said resultant, a second leadconnected to receive a Wave derived solely or combination irom one ormore of said primary Wave sources not supplying a component to saidresultant, each of said last two leads including a rectifier polarizedsimilarly to said first mentioned rectifiers relative to said sourcesand said last two leads being connected to a second common iunctionremote from said sources relative to said rectifiers therein, and meansfor applying said second Wave combination to the circuit of one of saidinformation channels to control the transmission of the signal thereinto said output path.

2. The combination defined in claim 1 wherein the primary Waves suppliedby said sources and the combinations thereof comprise pulses of enerallysquare wave form.

3. In circuit means for forming sequences of pulses by combiningportions of periodic voltage waves the co nbination which comprises asupply of regularly recurrent input pulses; a counting circuit actuatedby said pulses and having a chain of binary counting units each adaptedto supply two output voltage waves varying synchronously and oppositelyin amplitude responsive to the counting of such input pulses; circuitmeans for effecting corn binations of selected first groups of suchWaves, the means for efiecting each combination comprising leadsconnected to appropriate ones of said sources to receive the selectedwaves and a crystal diode rectifier connected in each lead, the leadsfor combining the Waves of each group being connected to a commonjunction at points thereof remote from said binary units relative tosaid rectifiers and said rectifiers being similarly polarized relativeto current from said units; and circuit means for etiecting combinationsof second groups of said waves Which respectively include selected onesof said first groups in the combined forms thereof appearing at saidjunctions, the means for efiecting each of said last mentionedcombinations comprising at least one lead connected to one of saidcommon junctions and including therein a crystal diode rectifierpolarized similarly to said first rectifiers relative to current fromsaid units.

4. The combination defined in claim 3 wherein said counting circuitcomprises means adapting it to count to a scale other than an integralpower or" two.

5. In circuit means for forming sequences of pulses by combiningportions of periodic voltage .Waves the combination which includes asupply of regularly recurrent input pulses; a counting circuit actuatedby said pulses and having a chain of binary counting units each adaptedto supply two ouput voltage waves varying synchronously and oppositelyin amplitude responsive to the counting of such input pulses; means foreffecting combinations of portions of the waves of selected first groupsof such voltage waves including means operative to select in the groupat each instant the Wave portion having the greatest amplitude of aconstant predetermined sign and to supply as the combined wave acontinuous sequence of such wave portions; and means for efiecting insimilar manner combinations of wave portions of selected second groupsof the said voltage waves supplied by said counting circuit, said secondwave groups respectively including as a component thereof at least oneof the combined waves resulting from the operation of said firstcombining means.

6. The combination defined in claim 5 wherein said wave portionselection means for each group of Waves comprises a group of rectifiersequal in number to the waves of the selected group having terminals ofone character commonly connected and terminals of the opposite characterrespectively connected to the sources of the waves of the selectedgroup.

7. In a circuit for sending out over a single output path recurrentsequences of samples of the variable signals of a plurality ofinformation channels by applying to the channels in sequence samplingpulses conditioning the circuit to transmit said signals to the outputpath for the duration of the pulses, the means for donning said pulseswhich comprises a plurality of sources or" primary periodic voltageWaves, means for efiecting the combination of a first selected group ofsaid primary Waves including leads respectively connected to the sourcesof said Waves each having a rectifier therein, said rectifiers beingsimilarly polarized relative to said sources and said leads beingconnected to a common junction remote from said sources relative to saidrectifiers, means for effecting the combination or" second selectedgroups of said primary Waves each including said first combination as itappears at said junction comprising leads of a first category connectedto said junction to receive said result ant thereat and leads of asecond category connected to receive waves derived solely or incombination from ones of said primary Wave sources not supplying acomponent to said resultant, each lead of said categories including arectifier polarized similarly to said first-mentioned rectifiersrelative to said sources and groups of such leads each including a leadof said first and of said second category being commonly connected toindividual junctions remote from said sources relative to saidrectifiers, and means for applying the second wave combinations thusmade to selected ones of said information channels, respectively, tocontrol the transmission of the signals therein to said output path.

References Cited in the file of this patent UNITED STATES PATENTS2,563,589 Hertog Aug. 7, 1951 2,570,716 Rochester Oct. 9, 1951 2,595,378Hertog et a1. May 6, 1952 2,688,661 Van Mierlo Sept. 7, 1954

